Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
CHEATHAM J DOUGLAS
  2. Issuer Name and Ticker or Trading Symbol
OLD SECOND BANCORP INC [OSBC]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
CFO
(Last)
(First)
(Middle)
37 S. RIVER ST.
3. Date of Earliest Transaction (Month/Day/Year)
03/31/2006
(Street)

AURORA, IL 60506
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Old Second Bancorp Inc. Common Stock 03/31/2006   (1) J   201 A (2) 2,975 (2) I 401(k) Plan
Old Second Bancorp Inc. Common Stock 03/31/2006   (1) J   203 A (3) 2,460 (3) I Pr. Sh. Plan
Old Second Bancorp Inc. Common Stock               1,400 D  

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Employee Stock Option (Right to Buy $ 31.34             12/20/2005 12/21/2015 Common Stock 12,000   12,000 D  
Employee Stock Option (Right to Buy $ 32.59             12/20/2005 12/21/2014 Common Stock 12,000   12,000 D  
Employee Stock Option (Right to Buy) $ 25.08             12/20/2005 12/16/2013 Common Stock 12,000 (4)   12,000 (4) D  
Employee Stock Option (Right to Buy) $ 18.81             12/20/2005 12/17/2012 Common Stock 12,000 (4)   12,000 (4) D  
Employee Stock Option (Right to Buy $ 14.74             12/20/2005 12/19/2011 Common Stock 10,666 (5)   10,666 (5) D  
Employee Stock Option (Right to Buy $ 10.46             12/20/2005 12/14/2009 Common Stock 6,666 (5)   6,666 (5) D  
Employee Stock Option (Right to Buy $ 8.91             12/20/2005 12/18/2010 Common Stock 12,000 (5)   12,000 (5) D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
CHEATHAM J DOUGLAS
37 S. RIVER ST.
AURORA, IL 60506
  X     CFO  

Signatures

 /s/ J. Douglas Cheatham   03/31/2006
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Does not apply.
(2) Of this total, 201 shares were allocated during the fourth quarter pursuant to the Old Second Bancorp Inc. Salary Savings Plan & Trust. Information provided herein is based on information provided by the Plan Trustee as of 03-31-06.
(3) Of this total, 203 shares were allocated during the fourth quarter pursuant to the Old Second Bancorp Inc. Employees Profit Sharing Plan & Trust. Information provided herein is based on information provided by the Plan Trustee as of 03-31-06.
(4) Shares restated for a 2 for 1 stock split effected in the form of a stock dividend and payable 7-28-04.
(5) Shares restated for a 4 for 3 stock split effected in the form of a stock dividend and payable 6-24-02 and restated for a 2 for 1 stock split effected in the form of a stock dividend and payable 7-28-04.

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